Non-return valve for bore hole sleeves

ABSTRACT

A non-return valve for bore hole sleeves, which are intended for injection of a sealing and/or reinforcing compound into rock cracks and similar cracks and which comprise a rigid case (10), one end (10A) of which is provided with means for detachable connection to the case of a pump hose (12) for the compound to be injected, as well as an expandable device (15) for securing the rigid case in the bore hole (21), comprises an elastic sleeve (22) which is adapted at the other end (10B) of the rigid case (10) in such a way that the rigid case (10) runs into the elastic sleeve (22). The elastic sleeve is adapted for automatical contraction, when no compound is being injected through the elastic sleeve, so that already injected compound can not flow backwards into the rigid case (10). The sleeve (22) is preferably provided with diametrically positioned clamp means (23-26) at its free ends, so that the free end of the sleeve has a flat shape, when no compound is being injected through the elastic sleeve. When compound is to be injected through the elastic sleeve, the sleeve is expanded by the pressure of the compound, so that the flow area of the elastic sleeve is increased. When the injection pressure ceases, the sleeve is contracted. The pressure outside the sleeve conduces to the contraction of the sleeve, so that no injected compound can be forced backwards through the elastic sleeve.

BACKGROUND OF THE INVENTION

The present invention relates to a non-return valve for bore holesleeves which are intended for injection of a sealing and/or reinforcingcompound into rock cracks and similar cracks and which comprise a rigidcase, one end of which is provided with means for detachable connectionto the case of a pump hose for the compound to be injected, as well asan expandable device for securing the rigid case in the bore hole.

When bore hole sleeves are used, said sleeves are first fixed by meansof the expandable device in holes that have been bored in the rock. Thesealing and/or reinforcing compound is then injected through the borehole sleeves into the rock crack. The bore hole sleeves have to beprovided with a non-return valve of some type to prevent the compoundfrom flowing back through the bore hole sleeves, when the pump pressureceases.

The non-return valves which hitherto have been used in connection withbore hole sleeves have comprised a movable mechanical valve means, forexample a ball, as disclosed in the German Patent Application No. 2 402509. A non-return valve of this type has two disadvantages. Firstly, itis difficult to achieve a reliable operation of the valve means duringthe heavy working conditions prevailing during injection of, forexample, cement grout or a similar sealing compound under high pressureinto rock cracks. Secondly, the valve element obstructs the injection ofthe compound due to the fact that the flow area of the bore hole sleeveis reduced. It is particularly difficult to use a ball valve asnon-return valve in connection with a bore hole sleve of the typedisclosed in the Swedish Patent Application No. 8204256-5, where ablocking means is provided at the exit end of the bore hole sleeve toenable the establishment of an initial pressure in the bore hole sleeveto actuate the expandable means. The blocking means is then forced outof the bore hole sleeve by further increasing the pressure in the borehole sleeve. Furthermore, non-return valves comprising balls or othermovable valve means and corresponding valve seats are expensive tomanufacture.

SUMMARY OF THE INVENTION

The main object of the invention is to provide a non-return valve whichdoes not have the above mentioned disadvantages. According to theinvention, this is achieved by giving the non-return valve the featuresset forth in the claims.

Due to the fact that the non-return valve is an elastic sleeve intowhich the rigid case of the bore hole sleeve runs and which is adaptedfor automatical contraction, when no compound is being injected, areliable valve operation is achieved and a flow area for the injectedcompound in the non-return valve is provided which has substantially thesame size as the flow area in the rigid case of the bore hole sleeve, sothat the non-return valve does not obstruct the injection of thecompound into a rock crack. Due to the fact that the elastic sleeve isexpanded and contracted, no movable valve means with valve seats arerequired, thus increasing the reliability of the operation of thenon-return valve and substantially reducing the manufacturing cost ofthe non-return valve. Particularly by providing contraction means at thefree end of the elastic sleeve in such a way that they cause aflattening of the exit end of the elastic sleeve, a very reliable valveoperation is achieved, because the backward flow of the compoundconduces to the compression of the mouth of the elastic sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of a non-return valve according to the invention will nowbe further described below with reference to the accompanying drawings.

FIG. 1 is a longitudinal section of a bore hole sleeve which is insertedinto a bore hole and which has a non-return valve according to theinvention and an expandable device.

FIG. 2 is a longitudinal section of the bore hole sleeve shown in FIG.1, the section being rotated 90° in relation to the section of FIG. 1and the sleeve being fixed in the bore hole by means of the expandabledevice.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The bore hole sleeve shown in FIGS. 1 and 2 comprises a rigid case 10,preferably of metal, for example aluminium. The case is at one end 10Aprovided with internal threads 11 for connection to a pump hose 12provided with external threads 13. At the opposite end 10B of the case ablocking means in the shape of a plug 14 is inserted in such a way thatthe plug loosens and is pushed out of the case 10, when the pressure inthe case exceeds a certain predetermined value. An elastic rubber sleeve15 surrounding the rigid case 10 is provided on the outside of the case10. The ends 15A and 15B of the rubber sleeve are attached to the rigidcase 10, for example by vulcanization. Two openings 16,17 are providedin the wall of the rigid case 10, so that the inside of the rigid caseis connected to the space 18 between the rigid case 10 and thesurrounding rubber sleeve 15. A non-return valve 19,20 is provided atboth these openings. This non-return valve consists of a rubber membrane20 attached to the outer wall of the rigid case in such a way that themembrane at least at one point can be lifted up from the wall of therigid case and form a channel connection for a pressurized compound fromthe inside of the rigid case to the space 18 between the rigid case 10and the rubber sleeve 15. The lifting occurs, when the pressure in therigid case exceeds a certain value. Pressurized compound can then beintroduced from the inside of the rigid case to the space between thesleeve 15 and the case 10, so that the rubber sleeve is forced to expandand to abut against the wall 21 of the bore hole. When the pressure inthe rigid case is reduced, the introduced compound can not return to therigid case, because the membrane then closes the opening in the wall ofthe rigid case. Thus, the membrane will operate as a non-return valve.The non-return valve is so designed that it allows introduction ofpressurized compound in the space between the rigid case and the rubbersleeve at a pressure level which is below the pressure level at whichthe plug 14 is pushed out of the rigid case.

An elastic sleeve 22 is attached to the exit end 10B of the rigid casein such a way that the rigid case runs into the elastic sleeve. Theelastic sleeve is at its free end provided with clip means 23,24 and25,26 which give the elastic sleeve a flattened shape at the free end,i. e. at the exit opening of the sleeve. These clip means are in thedisclosed embodiment staples which are forced through the wall of thesleeve and pass through the wall two times, so that two projecting folds27,28 are formed on the wall of the elastic sleeve. Two staples 23,24and 25,26 are provided on either side of the elastic sleevediametrically in relation to the central axis of the elastic sleeve 22,so that the two folds 27,28 are diametrically positioned at the exit endof the sleeve. The folds give the exit end of the sleeve a flattenedshape, so that the exit opening has the shape of a narrow slot in therest position of the sleeve. The staples 23,24 and 25,26 are sopositioned that each staple has its longitudinal direction in parallelwith the longitudinal axis of the elastic sleeve, so that the folds27,28 are as low as possible.

The elastic sleeve 22 can be attached to the exit end 10B of the rigidcase by means of a hose clamp 29 or by vulcanization.

The operation of the elastic sleeve 22 as non-return valve is asfollows. In the idle state, i. e. when no compound is being injectedthrough the bore hole sleeve, the exit opening of the sleeve has theshape of a narrow slot. When a compound is being injected through thebore hole sleeve, the exit opening of the elastic sleeve is expanded dueto the elasticity of the sleeve, so that the exit opening gets asubstantially round shape and obtains about the same flow area as therigid case 10 of the bore hole sleeve, so that the non-return valve doesnot provide an obstruction neither for the plug 14, when the plug ispushed out of the rigid case, nor for the compound to be injected. Whenthe injection is finished, i. e. when the rock crack is filled with thesealing and/or reinforcing compound, the pumping is discontinued. Thepressure in the rigid case 10 and the elastic sleeve 22 is thensubstantially reduced. Due to the operation of the applied staples23-26, the exit end of the sleeve endeavours to contract to theflattened shape. Due to the fact that the sleeve is still filled withcompound under a certain pressure, the sleeve can contract itself onlypartly by its own effort. However, the pressure in the compound that hasbeen injected into the rock crack and lies around the elastic sleeve isnow higher than the pressure in the elastic sleeve and provides theflattening of the mouth of the sleeve required to prevent injectedcompound to be forced backwards from the rock crack into the rigid caseand thus in opposite direction through the bore hole sleeve.

The very simple design of the non-return valve according to theinvention makes the non-return valve very reliable in operation.Therefore, the pump hose can be disconnected from the bore hole sleeveimmediately without any risk that the pressure in the cement groutinjected into the bore hole is reduced, before the cement is completelyburned. This makes the non-return valve very time-saving.

While only one embodiment of the non-return valve according to theinvention has been shown and described above, it is obvious that manymodifications and variations are possible within the scope of theinvention. For example, it is possible to vary the number of staples andthe position of the staples, so that the formed, diametricallypositioned folds get another length and another width. Furthermore, itis possible to use other mechanical means than staples to provide thediametrical folds, for example U-shaped bars or loops that are clampedto the wall of the elastic sleeve without passing through the wall. Ifthe elastic sleeve consists of a very soft material, the exit opening ofthe sleeve can also be contracted maintaining the round shape. Thecontracting means may then consist of for example one or more elastic orresilient rings arranged to surround the sleeve. The contracting meansneed not necessarily be positioned at the exit end of the elastic sleevebut can be positioned more towards the middle of the sleeve. Thecontracting ability of the sleeve can also be provided by the choice ofa suitable elastic material and of a suitable shape of the sleeve, sothat there is no need to provide the sleeve with special mechanicalcontracting means. For example, if the sleeve is provided with a conicalor otherwise tapering free end, the free end of the sleeve will beexpanded during the injection of compound and contracted, when theinjection pressure ceases. The sleeve must not necessarily be adapted toreduce the flow area to zero, but a certain open area can be allowed inthe sleeve in the contracted state of the sleeve, as the pressureoutside the sleeve can provide the complete closure of the elasticsleeve, so that no injected compound can pass backwards through thenon-return valve into the bore hole sleeve.

What we claim is:
 1. A non-return valve for use with a bore hole sleevefor injecting a sealing and/or reinforcing compound into rock cracks andsimilar apertures, the bore hole sleeve including a rigid case (10), oneend (10A) of which is provided with means for detachable connection tothe case of a pump hose (12) for the compound to be injected, as well asan expandable device (15) which is mounted on the rigid case and whichis expandable into engagement with the wall of the bore hole to securethe rigid case in the bore hole (21), said non-return valve comprising:an elastic sleeve (22) which is connected at the other end (10B) of therigid case (10) in such a way that the rigid case (10) runs into theelastic sleeve (22); and contraction means for flattening the free endof the elastic sleeve when no compound is being injected so thatalready-injected compound cannot flow backwards into the rigid case(10), the contraction means including mechanical means adjacent the freeend of the elastic sleeve for providing two projecting folds (27, 28) inthe wall of the elastic sleeve, the projecting folds being diametricallypositioned in relation to each other.
 2. A non-return valve according toclaim 1, wherein the contraction means are mechanical clamps (23-26). 3.A non-return valve according to claim 2, wherein the mechanical clampsconsist of at least one staple (23,25) on either side of the elasticsleeve (22), each staple passing two times through the wall of theelastic sleeve (22).
 4. A non-return valve according to claim 3, whereineach staple (23-26) has its longitudinal direction in parallel with thelongitudinal axis of the elastic sleeve (22).
 5. A bore hole sleeve forreceiving flowable material that is forced through a conduit and forinjecting the flowable material into a bore hole, comprising:a rigidtubular case having first and second ends and having a lateral openingbetween the first and second ends; means for connecting the first end ofthe case to the conduit; an expandable first sleeve disposed around thecase, the first sleeve having end regions which are sealingly connectedto the case and having a central region which is not sealingly connectedto the case, the lateral opening in the case being positioned tocommunicate with the central region of the first sleeve; a one-way valvefor the lateral opening in the case; a flexible second sleeve havingfirst and second ends; means for connecting the first end of the secondsleeve to the second end of the case, the second sleeve and casetogether defining a flow path along which the flowable material istransferred from the conduit to the bore hole; first closure means fortemporarily closing the flow path, as flowable material is being forcedthrough the conduit, until the first sleeve has been expanded byflowable material into pressing contact with the wall of the bore holeto secure the case in the bore hole; and second closure means,cooperating with the second sleeve, for causing the second sleeve tocollapse and close the flow path when flowable material is no longerbeing forced through the conduit, the second closure meansincludingfirst elongated pinch means, disposed transverse to the secondend of the second sleeve, for pinching the wall of the second sleevetogether, and second elongated pinch means, disposed transverse to thesecond end of the second sleeve and spaced apart from the first pinchmeans, for pinching the wall of the second sleeve together.
 6. The borehole sleeve of claim 5, wherein the first and second pinch means piercethe second sleeve.
 7. The bore hole sleeve of claim 6, wherein the firstand second pinch means are disposed adjacent the second end of thesecond sleeve.
 8. The bore hole sleeve of claim 7, wherein the first andsecond pinch means comprise staples.
 9. The bore hole sleeve of claim 5,wherein the first closure means comprises a plug releasably closing thesecond end of the case.
 10. The bore hole sleeve of claim 5, wherein theone-way valve comprises a flexible membrane disposed between the caseand the first sleeve, the membrane being positioned to cover the lateralopening in the case.
 11. The bore hole sleeve of claim 10, wherein theflexible membrane is a resilient band around the case.
 12. The bore holesleeve of claim 5, wherein the means for connecting the first end of thecase to the conduit comprises selectively actuatable means for releasingthe connection so that the conduit can be removed, leaving the bore holesleeve in the bore.
 13. The bore hole sleeve of claim 12, wherein theselectively actuatable means comprises screw threads.